To determine by means of a randomized clinical trial whether argon laser photocoagulation when used to obliterate extrafoveal choroidal neovascularization can prevent visual acuity loss in patients with senile macular degeneration and ocular histoplasmosis. To document the natural history of subfoveal choroidal neovascular membranes in patients with senile macular degeneration and ocular histoplasmosis. To document the natural course of macular drusen and macular "histo spots" in the fellow eyes of patients who have choroidal neovascularization in the first eye; specifically to quantify the rate at which such eyes develop choroidal neovascularization. To document the natural course of serous detachments of the retinal pigment epithelium (RPE) ("avascular disciforms") in eyes with senile macular degeneration. To develop a randomized trial for subfoveal choroidal neovasculaziation in ocular histoplasmosis and senile macular degeneration and to develop a randomized trial for serous detachments of the RPE in senile macular degeneration pending the outcome of the natural history studies outlined above.